2Definition  (Quadratic Growth (QG) condition [1]})  
The set of functions satisfying the QG condition with parameter \(C\) , denoted \(\mathrm {QG} (C)\)  is defined by the inclusion, \(g : \mathbb {R}^m \rightarrow \mathbb {R}\)  belongs to \(\mathrm {QG} (C)\)  iff for some \(z^* \in \operatornamewithlimits{arg\,min}_{z \in \mathbb {R}^m} g(z)\)  and for all \(z \in \mathbb {R}^m\) ,
\(g(z) - g(z^*) \ge C \Vert  z^* - z \Vert _2^2.\) 
